1. Field of the Invention
This invention relates generally to a system and method for estimating the thickness of a vehicle brake pad as it wears from use and, more particularly, to a system and method that uses sensor fusion and brake modeling for estimating the thickness of a vehicle brake pad as it wears from use.
2. Discussion of the Related Art
Vehicle brake pads typically last between 20,000 and 80,000 miles depending on the type of driving, i.e., city, highway, rural, etc., where the average brake pad life is about 50,000 miles. The thickness of the brake pad gradually decreases as a result of wear as it is used. When the thickness of the brake pad becomes sufficiently small, a mechanical scraper makes contact with the brake rotor. The mechanical scraper makes an annoying high frequency noise, which is an unfriendly reminder that the brake pad needs to be replaced. Although the noise does alert the vehicle operator that the brake pad is worn out, it does not give the vehicle operator advanced warning, or a continuous determination the lining thickness, only that the brake pad has worn down to a low level. Therefore, for example, if a long trip is planned, there is no indication that the brake pads may not last the journey.
It is known in the art to provide a sensor that determines brake pad thickness as it wears. For example, sensors are known that include one or more wires extending across the brake pad at certain thickness levels so that when the wire breaks, the sensor will provide an indication that the brake pad thickness has been reduced a certain amount. However, such sensors are typically expensive, and do not provide a continuous indication of brake pad thickness through the life of the brake pad.